Infrastructure Top-Level Domain

Under this category, there is only one TLD – .arpa

This TLD is used exclusively for technical infrastructure purposes.

While the name was originally the acronym for the Advanced Research Projects Agency (ARPA), the funding organization in the United States that developed one of the precursors of the Internet (ARPANET), it now stands for Address and Routing Parameter Area.

Test top-level domains

The Internet Engineering Task Force reserved the DNS labels:

.example

.invalid

.localhost

.test

These TLDs cannot be installed into the root zone of the Domain Name System.

The reason for reservation of these top-level domain names is to reduce the likelihood of conflict and confusion. This allows the use of these names for either documentation purposes or in local testing scenarios.

I hope now you know what is a TLD

To re-cap, each TLD includes an independent registry controlled by a specific organization. Which is managed under the guidance of the Internet Corporation for Assigned Names and Numbers (ICANN).

If you have any questions, feel free to ask in the comment section below.

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